I’ve heard both speakers. In both instances I was at shows so not ideal listening environments. I heard the Razz speakers at the NYC audio show this past September and the Source Point 10 speakers 10 days ago. Based strictly on those experiences I’d choose the Volti speakers. To my ears they treat the mids and highs more gently than do the SP 10. I think the Razz provides more of a warmish natural sound than the SP10. Bass is outstanding on both. Of course, different rooms, electronics and recordings. Perhaps if I’d heard the SP 10s with the same 300b amp I’d feel differently.